1. Field of the Invention
The present invention relates to a solid state image device and a manufacturing method thereof, and more particularly, it relates to a solid state image device including a solid state image sensor having a photoelectric conversion function and a manufacturing method thereof.
2. Description of the Background Art
A solid state image device comprising a solid state image sensor having a photoelectric conversion function is known in general. FIG. 21 schematically illustrates the overall structure of a conventional solid state image device. FIG. 22 is a sectional view of a solid state image sensor part of the conventional solid state image device shown in FIG. 21. The structure of the conventional solid state image device is now described with reference to FIGS. 21 and 22.
In the conventional solid state image device, an optical lens 104 for condensing reflected light from an object is provided above a solid state image sensor 103 through an air space 105 having a refractive index of 1, as shown in FIG. 21.
More specifically, photoreceptive parts 107 having photoelectric conversion functions of converting incident light to signal charges are formed on prescribed regions of an Si substrate 106, as shown in FIG. 22. An interlayer dielectric film 108 is formed on the Si substrate 106 formed with the photoreceptive parts 107. Shielding films 109 are formed on prescribed regions of the interlayer dielectric film 108. These shielding films 109 have functions of preventing the prescribed regions from incidence of light. Another interlayer dielectric film 110 is formed to cover the shielding films 109 and the interlayer dielectric film 108. A resin film 111 having upwardly projecting portions 111a and flat portions 111b is formed on the interlayer dielectric film 110. This resin film 111 has a refractive index of about 1.5. The projecting portions 111a of the resin film 111 have functions serving as microlenses condensing light. In other words, the surfaces of the projecting portions 111a of the resin film 111 inwardly refract light incident upon the air space 105 through the optical lens 104 (see FIG. 21) due to the refractive index (about 1.5) of the resin film 111 larger than the refractive index (1.0) of the air space 105. Thus, the photoreceptive parts 107 condense light incident upon the projecting portions 111a of the resin film 111.
Following recent miniaturization of a portable apparatus or the like mounted with such a solid state image device, miniaturization of the solid state image device has also been required. However, the conventional solid state image device, including the solid-state image sensor 103 and the optical lens 104, shown in FIG. 21 is hard to miniaturize due to the solid state image sensor 103 and the optical lens 104 separately provided through the air space 105.
In order to miniaturize such a solid-state image device, there has generally been proposed a solid state image device formed by bonding a solid state image sensor and an optical lens to each other through a resin layer thereby integrating the solid state image sensor and the optical lens with each other.
In the aforementioned generally proposed solid state image device, however, the resin layer having a refractive index of about 1.5 is used for bonding the solid state image sensor and the optical lens to each other. When a conventional resin film having a refractive index of about 1.5 for serving as a microlens is formed on the solid state image sensor in this case, it is inconveniently difficult to refract light incident upon the resin film serving as a microlens from the resin layer due to the substantially identical refractive indices (about 1.5) of the resin layer serving as a bonding layer and the resin film serving as a microlens. In the generally proposed solid state image device, therefore, the solid state image sensor and the optical lens are bonded to each other through the resin layer serving as a bonding layer without forming a microlens on the solid state image sensor. Consequently, it is disadvantageously difficult to provide the solid state image device with high condensability when integrating the optical lens and the solid state image sensor with each other.